640 THE BUTTERFLIES OF NEW ENGLAND. 



flies until November. Edwards himself thinks there must be six or seven ; 

 probably it would be quite impossible to tell. 



An interesting feature in the history of this butterfly is the lethargy of 

 the caterpillars already alluded to. Mr. Edwards finds that in West Vir- 

 ginia this peculiarity does not appear in the earlier broods, but only in the 

 last two broods of larvae : and while invariable in those of the last brood 

 which Avinter, but sometimes become lethargic as early as the end of August, 

 to judge from his account it also appears in the larvae of the preceding 

 brood, some of which become lethargic in very warm weather, while the 

 greater number proceed regularly, like the caterpillars of the preceding- 

 broods, to chrysalis. Our knowledge of their behavior in the north is 

 entirely due to the accounts of Mr. Edwards, and are not founded on 

 experiments conducted wholly there. Caterpillars from eggs laid at the 

 end of July, and therefore of the second brood of Isutterflies, all became 

 lethargic after the second moult, or about September 4 ; but two weeks 

 later part of them resinned activity, fed a few days, passed another moult 

 and then became lethargic again. These were placed in a cellar and 

 remained without change through the winter. On another occasion eggs 

 laid in the middle of August, in Coalburgh, were taken to the Catskills 

 where they hatched on the 20th. After the second moult a portion, 

 about 40 per cent, became lethargic, while the remainder continued their 

 changes until the butterflies appeared (September 15-2G) : some of the 

 chrysalids were kept in a cool place in Albany and gave out butterflies be- 

 tween October 21 and November 2. All this is of course not what happens 

 freely in the Catskills under natural conditions, for it is safe to say that no 

 butterflies emerge there as late as the middle of September. But it is inter- 

 esting to note that about one half of the 40 per cent which became lethargic 

 began to feed again about September 2(3, passed another moult and then re- 

 sumed their lethargy. A third experiment showed that eggs laid in the Cats- 

 kills at the end of June by butterflies of the first brood, and carried to 

 "West Virginia hatched there July 3, and most of them gave butterflies by 

 the end of the month, l)ut a portion even in this southern locality (about 

 5 per cent) became lethargic after the second moult, a thing which Mr. 

 Edwards has not found to occur with West Virginian larvae at that season. 

 This leads him to conclude that probably a portion of the caterpillars from 

 the first brood of butterflies in the north become letliargic and continue so 

 until the following spring, i. e., that in the north the species is partly 

 monogoneutic and partly digoneutic, and that in the northernmost part of 

 its range, to judge from the short season and dates of flight of the butter- 

 fly, it is monogneutic only ; for instance, in southern Labrador and Anti- 

 costi the butterfly is not seen after June ( though it has been taken on the upper 

 Liard July 13 and at Edmonton July 15). This conclusion is in the 

 highest degree probable, and the proportion of the caterpillars from the 



